1. Field of the Invention
This invention generally relates to a smoke generator and a method of generating smoke and, more particularly, to a novel gas turbine exhaust arrangement operative for vaporizing fog oil to generate smoke.
2. Description of Related Art
There are many applications, particularly in the military, for generating smoke. Liquid materials, such as fog oil, are vaporizable at about 900.degree. F. to produce smoke. However, heat generators capable of achieving such elevated vaporization temperatures are not readily available in the field. For example, small gas turbines having, inter alia, a compressor for drawing fresh air into a combustion chamber where fuel is burned, and a bladed rotor turnable by the combustion gases, discharge hot exhaust gases from the rotor at a temperature, under normal operating conditions, of about 500.degree. F. which is substantially lower than that needed to vaporize fog oil.
In order to raise the temperature of the exhaust gases, it was known to bleed off some air from the compressor. A control valve was installed at the compressor, and was operative to direct some of the air drawn into the compressor into the ambient environment. By admitting less air into the combustion chamber, the temperature of the exhaust gases was raised to the aforementioned fog oil vaporization temperature.
Although there are many different types of gas turbines currently available in the inventory of the U.S. Armed Forces, many have no bleed air control valve to regulate the temperature of the exhaust gases. Complicated gas turbine modifications would be required to install such control valves and other associated control components. In some cases, such modifications cannot be done due to the design integrity of the turbine, because to implement such modifications would cause the overall performance of the turbine to be compromised.